Trump said the US refused to sign because “Canada is charging massive tariffs to our US farmers, workers and companies”.

US national trade adviser Peter Navarro joined the fray. “There is a special place in hell for any leader that engages in bad faith diplomacy with President Donald J Trump,” he said.

The furore partly flows from the White House using chaos in order to always appear on the front foot.

“I like chaos. It really is good,” Trump told journalists when he launched his proposals for tariffs on steel and aluminium last month.

And before the G7 summit, Trump threatened, “If we can’t make a deal we’ll terminate [trade agreement] Nafta”. Such a serious move would pit the White House against Mexico, Canada and much of US big business.

Trump’s trade wars can be a precursor towards intensified nationalist rivalries—and further pressure for military competition.

The trade row shows up splits in the Trump administration—and its frictions with sections of US capital.

A trade war is not in the interests of the capitalist class as a whole. Navarro said that tariffs would “reclaim the supply chain” and bring manufacturing back to the US.

The problem is that those global supply chains are profitable for US capitalists.

Opposing

These fissures don’t mean corporate tax-cutter Trump and capital are in two opposing camps.

He stands in a long line of presidents who have sought to defend US capitalism’s interests in the world.

The differences are over what’s the best way to do this.

While the US remains the largest military superpower, it faces increasing economic competition from China.

It’s tried a number of ways of dealing with this. George Bush murdered a million Iraqis. Controlling the tap on the world economy would have sent a message to China and the US’s other rivals.

The US defeat in Iraq forced Barack Obama to change tack. He shifted the US’s resources to the Pacific in the “pivot towards Asia”.

Trump has tried to return to a go it alone strategy—even threatening nuclear war with North Korea.